高寒高铁套管骤变温度场下微水相变对绝缘破坏的机理研究

With the rapid development of China's high-speed railway to the frontier provinces in China and the overseas, more and more high speed railway trips have been operated and designed to be built in alpine areas. It has been found that the destructive rate of bushings in alpine areas is higher than the bushings employed in the high-speed railway of other areas, and it is also higher than the bushings employed in normal-speed railway, which are the most important equipment in traction power system. After field anatomies, there are obvious crystallizations in the insulation interface of broken bushings employed in the alpine areas. The high-speed railway is of characteristic of “frequent in day and no in night”. Under the high-altitude and cold conditions, when the train park in night and depart in morning, the temperature of internal insulation of oil-immersed bushing could complicated change tens Celsius from higher than zero Celsius to less than zero Celsius. The phase changes of moisture in the internal insulation of bushings may result in the increasing of destructive rate, which are caused by the sudden changes of temperature. On the basis of designing experimental platform and conducting tests, a lot of experimental data could be obtained combined with numerical simulation and finite element method in the project. Then related studies would be conducted based on mathematical methods such as statistics and data mining. Finally, the following mechanisms would be obtained: ① characteristics of changes of moisture phase in the internal insulation of oil-immersed bushings under the high-altitude and cold conditions; ② effects of changes of moisture phase on the electrical strength and the developments of defects of oil-immersed bushings. The studies in our project would be helpful to explaining the deterioration of bushing in alpine areas, and providing methods to decrease the destructive rate of bushing in alpine areas.

随着“中国高铁”向边疆省域发展并迅速走向海外，高寒地区已建有并进一步规划大量高速铁路。高寒地区已通车的多条高铁运行中发现：作为牵引供电系统重要设备之一的高压套管，其损坏率远高于其它地区高铁及高寒地区普速铁路，现场解剖发现故障套管绝缘界面存在着明显的结晶痕迹。由于高速铁路负荷具有“昼频夜空”的特点，高寒环境下夜间停车及清晨发车时套管内绝缘发生摄氏零上与零下之间几十度的温度骤变，由此引起油纸绝缘中微水相态变化是套管损坏率升高的潜在原因。本项目将以实验与测试为基础，结合数值模拟、统计分析和理论研究，拟找出：①骤变温度场下套管油纸绝缘微水相态及其变化特征，②骤变温度场下套管油纸绝缘微水相变对绝缘破坏的机理，从而为探明高寒地区高铁高压套管绝缘破坏机理，解决高寒地区高铁高压套管损坏率升高的问题提供可能的方法。

随着“中国高铁”的迅速走向海外以及国内高铁建设的蓬勃发展，高寒地区已有高速铁路通车并规划多条主干高铁。牵引变压器是牵引供电系统的最核心设备，高压套管起到将高低压引线从牵引变压器内部引出并与外部电气网络连接的重要作用。然而，高速铁路负荷具有“昼频夜空”的特点，易引起油纸绝缘中微水相态变化而导致套管损坏率升高。为此本项目将以实验与测试为基础，结合数值模拟、统计分析和理论研究，探索高寒地区高速铁路牵引供电系统中的高压套管在骤变温度场下的微水相变特性及其对绝缘破坏的影响机理，具体研究内容包括：1）通过现场测试、实验测试与数值模拟研究套管内绝缘温度场骤变过程中的动态分布特征及变化规律，研究骤变温度场下油中、纸中、油-纸-铝箔界面处微水的相态特征，确定了温度场、微水含量、微水相态及其变化过程之间的关系。2）构建套管内绝缘整体电场与局部电场的有限元模型，找出了微水相变过程各参数对套管内绝缘电场分布的影响特征，并通过实验确定了微水相态对套管电气强度的影响规律。3）开展微水相变下的耐压实验，解剖并分析击穿通道形态特征，确定了微水相变对套管内绝缘缺陷发展过程中电气参数的影响规律以及绝缘失效的影响机理。研究过程中取得以下成果：培养博士研究生2名、硕士研究生5名，发表SCI论文6篇，EI论文5篇，授权发明专利8项。